Liquid formulation containing a protein drug

ABSTRACT

Disclosed is a method of preparing a stabilized liquid formulation of a protein drug, comprising admixing a protein drug with a composition for stabilization, wherein the composition for stabilization comprises a surfactant, a buffer, and a liquid medium, and has a pH from about 5 to about 8.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2013-0034893 filed on Mar. 29, 2013 in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ELECTRONICALLY

Incorporated by reference in its entirety herein is a computer-readable nucleotide/amino acid sequence listing submitted concurrently herewith and identified as follows: One 131,430 Byte ASCII (Text) file named “715828Sequence.TXT,” created on Mar. 31, 2014.

BACKGROUND OF THE INVENTION

1. Field

Disclosed is a composition for the stabilization of protein drugs, including a surfactant and having pH ranging from greater than about 4.5 to about 8, a liquid formulation including a protein drug and the composition, and a method of stabilizing a protein drug using the composition.

2. Description of the Related Art

Protein preparations are prone to degradation due to the denaturation and aggregation of proteins during the production process of the preparations. It is believed that the instability of protein preparations is mainly caused by the formation of soluble/insoluble particles, and increases with storage time. In general, important matters to consider in the formulation of a protein drug are maintaining solubility, stability, and bioactivity of the protein.

Among protein drugs, immunoglobulins are relatively liable to form aggregates and particulates, and thus have the disadvantage of deterioration in stability when they are formulated into a liquid form for intravenous or subcutaneous injections. Such aggregation and particulation (formation of particulates) of proteins and subsequent decreases in the stability thereof are aggravated when protein drugs such as immunoglobulins or antibodies are formulated at high concentrations, giving rise to a great hindrance in the development of protein drug products.

There is therefore a need for developing a technology for maintaining and/or improving physical, chemical and biological stability of protein drugs by preventing proteins from forming aggregates and/or particulates in liquid formulations thereof.

BRIEF SUMMARY OF THE INVENTION

Provided are a composition for stabilizing a protein drug, and a liquid formulation including a protein drug and the composition.

In particular, one embodiment provides a composition for the stabilization of a protein drug, including a surfactant and having a pH ranging from greater than 4.5 to 8.

Another embodiment provides a liquid formulation of a protein drug including a protein drug and the composition for the stabilization of the protein drug.

Another embodiment provides a method of preparing a stabilized liquid formulation of a protein drug using the composition for the stabilization of a protein drug. The method of preparing a stabilized liquid formulation of a protein drug may further include a step of providing a protein drug to be stabilized, before the step of admixing. The protein drug may be an antibody.

Still another embodiment provides a method of stabilizing a protein drug using the composition for the stabilization of a protein drug. The method of stabilizing a protein drug may further include a step of providing a protein drug to be stabilized, before the step of admixing. The protein drug may be an antibody.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a process of developing a liquid formulation including a high concentration of an antibody according to one embodiment.

FIG. 2 is a graph showing the degree of aggregation of an antibody in a stressed condition (50° C.) depending on the pH of the liquid formulation.

FIG. 3 is a graph showing the degree of aggregation of an antibody in a stressed condition (50° C.) depending on pH, the content of an osmoregulating agent (also referred to as an “osmo-regulating agent” or “osmotic pressure regulating agent”) and the content of surfactant in the liquid formulation.

FIGS. 4A and 4B are graphs showing the degree of aggregation of an antibody in a stressed condition (40° C.) (4A) and at a refrigeratory temperature (2 to 8° C.) (4B) depending on the kind of buffer, the pH of the liquid formulation, and the elapsed time of storage.

FIG. 5 is a graph showing the activity of the anti-c-Met antibody in a liquid formulation containing sodium phosphate as a buffer.

FIG. 6 is a graph showing the activity of the anti-c-Met antibody in a liquid formulation containing succinic acid as a buffer.

FIG. 7 is a graph showing the activity of the anti-c-Met antibody in a liquid formulation containing histidine as a buffer.

FIG. 8 is a graph showing the activity of the anti-c-Met antibody in a liquid formulation containing citric acid as a buffer.

FIG. 9 is a graph showing predicted long-term stability of a liquid formulation according to one embodiment.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment provides a composition for stabilizing a protein drug, including a surfactant and a buffer, and having a pH ranging from greater than about 4.5 to about 8, particularly from about 5 to about 8, from about 5 to about 7.5, or from about 5 to about 7. The pH of the composition may be adjusted with the buffer. Therefore, the composition for stabilizing a protein drug may include a buffer in an amount to adjust the pH of the composition to a range from greater than about 4.5 to about 8, and particularly, from about 5 to about 8, from about 5 to about 7.5, or from about 5 to about 7. The composition may be in the form wherein its constituents are dispersed in a liquid medium.

The composition for the stabilization of a protein drug may have osmotic pressure ranging from about 250 to about 400 mOsm, particularly from about 280 to about 360 mOsm, or from about 300 to about 340 mOsm. The osmotic pressure may be controlled with an osmotic pressure regulating agent.

Another embodiment provides a liquid formulation of a protein drug including a protein drug and the composition for the stabilization of the protein drug.

Another embodiment provides a method of preparing a stabilized liquid formulation of a protein drug, including admixing a protein drug with the composition for the stabilization of the protein drug.

Another embodiment provides a method for stabilizing a protein drug, including admixing the protein drug with the composition for the stabilization of the protein drug.

The protein drug may be an antibody (e.g., a mouse antibody, a human-mouse chimeric antibody, a humanized antibody, or a human antibody) or an antigen-binding fragment of the antibody.

In some embodiments, liquid formulation of a protein drug is stable for 6 months or longer at room temperature (e.g., about 23° C. to about 27° C.). The liquid formulation is suitable for use in parenteral administration, particularly for use as an injection.

Hereinafter, the present disclosure will be described in detail.

The composition for the stabilization of a protein drug may be in a form where its constituents, such as a surfactant, are dispersed in a liquid medium. The liquid medium may be an oil or an aqueous medium such as water.

The composition for the stabilization of a protein may include a surfactant. In the composition for the stabilization of a protein drug, the surfactant plays a crucial role in stabilizing a protein drug by suppressing the shear stress-induced aggregation of the protein drug (refer to Example 1). So long as it is pharmaceutically acceptable and enables a protein drug to be uniformly dispersed in a liquid medium, any surfactant may be employed in the composition for the stabilization of a protein drug. The surfactant may be non-ionic, and maybe, but is not limited to, one or more selected from the group consisting of polysorbates (e.g., polysorbate 20 (polyoxyethylene (20) sorbitan monolaurate), polysorbate 40 (polyoxyethylene (20) sorbitan monopalmitate), polysorbate 60 (polyoxyethylene (20) sorbitan monostearate), polysorbate 80 (polyoxyethylene (20) sorbitan monooleate); where the numeral 20 following polyoxyethylene means a total number of the oxyethylene moiety (—(CH₂CH₂O)—)), poloxamer (PEO-PPO-PEO copolymer; PEO: poly(ethylene oxide), PPO: poly(propylene oxide)), polyethylene-polypropylene glycol, polyoxyethylene compounds (e.g., polyoxyethylene-stearate, polyoxyethylene alkyl ether (alkyl: C1-C30), polyoxyethylene monolauryl ether, alkylphenyl polyoxyethylene copolymer (alkyl: C1-C30) etc.), sodium dodecyl sulphate (SDS).

To exert a more effective suppressive effect against the formation of particles and aggregates of protein drugs, the composition for the stabilization of protein drugs may include a surfactant in an amount from about 0.01 to about 1% (w/v), based on the total volume of the composition, particularly in an amount from about 0.01 to about 0.5% (w/v), and more particularly in an amount from about 0.01 to about 0.1% (w/v).

The composition for the stabilization of protein drugs may have a pH of greater than about 4.5 to about 8, particularly from about 5 to about 7.5, and more particularly from about 5 to about 7. Within these pH ranges, protein drugs, for example, antibodies can be stably maintained. When the pH of the composition is higher or lower than the range, a protein drug in the composition becomes unstable and undergoes degradation or aggregation. Hence, the pH of the composition may be within the ranges listed.

In order to keep or adjust the pH of the composition within the desired range, a buffer may be employed in the composition.

As used herein, the term “buffer” refers to an agent functioning to maintain the pH of a solution within a predetermined range in an aqueous environment. So long as it keeps the pH of the composition for the stabilization of protein drugs within the above-stated pH range (from greater than about 4.5 to about 8, particularly from about 5 to about 8, more particularly about 5 to about 7.5, and still more particularly from about 5 to about 7), any buffer, whether organic or inorganic, may be used. The buffer may be, but is not limited to, one or more selected from the group consisting of organic acids, inorganic acids, and salts of the organic and inorganic acids. The buffer may be, but is not limited to, an organic or inorganic acid selected from the group consisting of succinic acid, acetic acid, citric acid, histidine, phosphoric acid, glycine, lactic acid, Tris, Bis-Tris, and a combination thereof, or may be selected from succinate, acetate, citrate, phosphate, lactate, sodium salt of the organic or inorganic acid, and a combination thereof. For use in the composition, the buffer may be used in a solution form (buffer solution) where it is dissolved in a liquid medium, such as water, and having a pH from about 5 to about 8, from about 5 to about 7.5, or from about 5 to about 7.

The content of the buffer in the composition for the stabilization of protein drugs may be capable of maintaining the pH of the composition within the desired range. For example, a buffer may be used in an amount from about 0.1 to about 1% (w/v), particularly in an amount from about 0.1 to about 0.75% (w/v), and more particularly in an amount from about 0.2 to about 0.5% (w/v), based on the total volume of the composition.

To be applied to a living body, the composition for the stabilization of protein drugs may have an osmotic pressure from about 250 to about 400 mOsm, particularly from about 280 to about 360 mOsm, and more particularly from about 300 to about 340 mOsm. Similar to that of blood, this osmotic pressure range makes it possible to apply the composition of the present disclosure as an injection to the body. An osmotic pressure may be measured using a vapor pressure osmometer, or a freezing-point depression osmometer

The composition for the stabilization of protein drugs may further include an osmotic pressure regulating agent to keep and/or adjust the osmotic pressure of the composition within the desired range. The osmotic pressure regulating agent may be a pharmaceutically acceptable salt, a sugar, an amino acid, or a combination thereof. Representative among osmotic pressure regulating agents are sodium, potassium, magnesium and calcium salts of organic or inorganic acids such as hydrochloric acid, succinic acid, sulfuric acid. In particular, the osmotic pressure regulating agent may be, but is not limited to, one or more selected from the group consisting of sodium chloride, sodium succinate, sodium sulfate, potassium chloride, magnesium chloride, magnesium sulfate, magnesium chloride, and a combination thereof, with a preference for sodium chloride. Alternatively, the osmotic pressure regulating agent may be a monosaccharide, a disaccharide, an oligosaccharide, a polysaccharide, or a combination thereof. For example, the osmotic pressure regulating agent may be, but is not limited to, one or more selected from the group consisting of trehalose, sucrose, mannitol, sorbitol, fructose, maltose, lactose, dextran, or a combination thereof. Further, the osmotic pressure regulating agent may be, but is not limited to, one or more selected from the group consisting of proline, alanine, arginine (e.g., L-arginine), asparagines, aspartic acid (e.g., L-aspartic acid), glycine, serine, lysine, and histidine.

The content of the osmotic pressure regulating agent in the composition for the stabilization of protein drugs is such that it guarantees the maintenance of the osmotic pressure of the composition within the desired range. For example, the osmotic pressure regulating agent may be used in an amount from about 0 to about 1% (w/v), particularly in an amount from about 0.01 to about 1% (w/v), and more particularly in an amount from about 0.5 to about 1% (w/v), based on the total amount of the composition.

In one embodiment, the composition for the stabilization of protein drugs include a surfactant in an amount from about 0.01 to about 1% (w/v), particularly in an amount from about 0.01 to about 0.5% (w/v), and more particularly in an amount from about 0.01 to about 0.1% (w/v), a buffer in an amount from about 0.1 to about 1% (w/v), particularly in an amount from about 0.1 to about 0.75% (w/v), and more particularly in an amount from about 0.2 to about 0.5% (w/v), and an osmotic pressure regulating agent in an amount from about 0 to about 1% (w/v), particularly in an amount from about 0.01 to about 1% (w/v), and more particularly in an amount from about 0.5 to about 1% (w/v), based on the total amount of the composition.

According to the present disclosure, as stated above, the liquid formulation of a protein drug includes a protein drug, and the composition for the stabilization of the protein drug. In the liquid formulation of a protein drug, the content of the protein drug may be about 1 mg/ml or greater, about 10 mg/ml or greater, about 20 mg/ml or greater, or about 25 mg/ml or greater. For example, the liquid formulation of a protein drug may include a drug protein in an amount from about 1 to about 200 mg/ml, about 1 to about 100 mg/ml, about 1 to about 50 mg/ml, about 10 to about 200 mg/ml, about 10 to about 100 mg/ml, about 10 to about 50 mg/ml, about 20 to about 200 mg/ml, about 20 to about 100 mg/ml, about 20 to about 50 mg/ml, about 25 to about 200 mg/ml, about 25 to about 100 mg/ml, or about 25 to about 50 mg/ml.

Even if it is present at a relatively high concentration (e.g., about 1 mg/ml or greater, about 10 mg/ml or greater, about 20 mg/ml or greater, or about 25 mg/ml or greater) in the liquid formulation of a protein drug, the protein drug is maintained stably without aggregation or degradation. The liquid formulation of a protein drug of the present disclosure is maintained stably at room temperature (about 23° C. to about 27° C.) for six months or longer, for example, for one year or longer, or for two years. At 2 to 8° C., the liquid formulation of a protein drug can be stored stably for a longer period of time, for example, one year or longer, or two years or longer.

The term “maintained stably” as used in the context of the storage of the liquid formulation of a protein drug of the present disclosure, may refer to keeping the protein drug intact in terms of physical stability, chemical stability and/or biological activity. Various analysis technologies for measuring the stability of proteins are well known in the art.

For instance, the stability of the liquid formulation of a protein drug may be evaluated, considering the aggregation of the protein drug as a main factor. Given a shear stress or a different physical or chemical condition, a protein drug may form into an aggregate. Because this aggregation can negatively influences the bioavailability of the protein drug, such as increased immunogenicity and decreased efficacy, it can be used as an important analytical index for the development of liquid formulations.

After being stored for three months in a stressed condition such as at 40° C. or higher (e.g., about 40° C. to about 50° C.), particular embodiments were found to retain about 95% or more, about 96% or more, or about 97% or more of the initial content of the protein drug as a monomeric form without aggregation or degradation. In other words, only about 5% or less, for example, about 4% or less, or about 3% or less of the initial content of the protein drug was found to aggregate or degrade after the liquid formulation of a protein drug was stored in a stressed condition (40° C. to 50° C.) for three months.

The composition or the liquid formulation may further include a carrier, a diluent and/or an excipient, which are all pharmaceutically acceptable. So long as it is known in the art, any pharmaceutically acceptable carrier may be used. Examples of the carrier include lactose, dextrose, sucrose, sorbitol, mannitol, starch, acacia gum, calcium phosphate, alginate, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrup, methyl cellulose, methylhydrobenzoate, propylhydroxybenzoate, talc, magnesium stearate, and mineral oil, but are not limited thereto.

The liquid formulation of a protein drug may be in an oral or parenteral dosage form. For parenteral administration, intravenous, subcutaneous, interamuscular, intraperitoneal, intradermal, topical, intranasal, intrapulmonary, and intrarectal injections may be used. When an oral route is taken, a protein drug must be protected from gastric digestion by coating or formulating it with an anti-peptic degradation agent. In addition, the composition may be administered with the aid of a device that helps the protein drug to reach target cells.

The protein drug may be an antibody or an antigen-binding fragment of an antibody. The antibody may be monoclonal or polyclonal, and may include a mouse antibody, a human-mouse chimeric antibody, a humanized antibody, a human antibody, but is not limited thereto.

In detail, the antibody may be specific to an antigen selected from among the following proteins or peptides:

renin; growth hormones including human growth hormone and bovine growth hormone; growth hormone releasing factor; parathyroid hormone; thyroid stimulating hormone; lipoproteins; alpha-1-antitrypsin; insulin A-chain; insulin B-chain; proinsulin; follicle stimulating hormone; calcitonin; luteinizing hormone; glucagon; coagulation factors, such as factor VIIIC, factor IX, tissue factor, Von Willebrands factor, etc.; anticoagulants, such as protein C; atrial natriuretic factor; pulmonary surfactant; plasminogen activator, such as urokinase or human urinary or tissue-type plasminogen activator (t-PA); RANTES (Regulated on Activation Normal T-cell Expressed and Secreted) (chemotactic for T cells); human macrophage inflammatory protein (MIP-1-alpha); serum albumin; Mullerian-inhibiting substance; relaxin A-chain; relaxin B-chain; prorelaxin; mouse gonadotropin-related peptide; microbial proteins such as beta-latamase; DNase; IgE; cytotoxic T-lymphocyte-related antigen (CTLA) such as CTLA-4; inhibin; activin; vascular endothelial growth factor (VEGF); receptors for hormones or growth factors; Protein A or D; rheumatoid factors; neurotrophic factors such as bone-derived neurotrophic factor (BDNF), and neurotrophin-3, -4, -5 and -6 (NT-3, NT-4, NT-5, and NT-6), or nerve growth factors such as NGF-β; platelet-derived growth factor (PDGF); fibroblast growth factors such as aFGF and bFGF; epithelial growth factor (EGF); transforming growth factor (TGF), such as TGF-α and TGF-β including TGF-β₁, TGF-β₂, TGF-β₃, TGF-β₄, and TGF-β₅; insulin-like growth factor-I and -II (IGF-I and IGF-II); des(1-3)-IGF-I (IGF-1 found in the brain), insulin-like growth factor binding protein; CD proteins such as CD3, CD4, CD8, CD19 and CD20; erythropoietin; osteoinductive factors; immunotoxins; bone morphogenic protein (BMP); interferons such as interferon-α, -β, and -γ; colony stimulating factors (CSF), such as M-CSF, GM-CSF, and G-CSF; interleukin (IL), such as IL-1 to IL-12; receptors for IL-1 to IL-12; selectin, such as L-, E-, and P-selectin; hydrogen peroxide dismutase; T-cell receptor; membrane surface protein; degradation-promoting factors; viral antigens such as AIDS envelope; transport protein; homing receptor; addressins; regulatory proteins; integrins such as CD11a, CD11b, CD11c, CD18, ICAM, VLA-4 and VCAM; EGFR, such as HER2, HER3 or HER4 receptor; and a fragment of any of the above-mentioned peptides, but is not limited thereto.

In a particular embodiment, the antibody may be an anti-c-Met antibody or an antigen-binding fragment thereof. The anti c-Met antibody may recognize any specific region of c-Met, e.g., a specific region in the SEMA domain, as an epitope. It may be any antibody or antigen-binding fragment that acts on c-Met to induce intracellular internalization and degradation of c-Met.

The “c-Met protein” refers to a receptor tyrosine kinase binding to hepatocyte growth factor. The c-Met proteins may be derived from any species, for example, those derived from primates such as human c-Met (e.g., NP_000236) and monkey c-Met (e.g., Macaca mulatta, NP_001162100), or those derived from rodents such as mouse c-Met (e.g., NP_032617.2) and rat c-Met (e.g., NP_113705.1). The proteins include, for example, a polypeptide encoded by the nucleotide sequence deposited under GenBank Accession Number NM_000245, or a protein encoded by the polypeptide sequence deposited under GenBank Accession Number NM_000236, or extracellular domains thereof. The receptor tyrosine kinase c-Met is involved in several mechanisms including cancer incidence, cancer metastasis, cancer cell migration, cancer cell penetration, and angiogenesis.

c-Met, a receptor for hepatocyte growth factor (HGF), may be divided into three portions: extracellular, transmembrane, and intracellular. The extracellular portion is composed of an α-subunit and a β-subunit which are linked to each other through a disulfide bond, and contains a SEMA domain responsible for binding HGF, a PSI domain (plexin-semaphorins-integrin homology domain) and an IPT domain (immunoglobulin-like fold shared by plexins and transcriptional factors domain). The SEMA domain of c-Met protein may have the amino acid sequence of SEQ ID NO: 79, and is an extracellular domain that functions to bind HGF. A specific region of the SEMA domain (SEQ ID NO: 71) corresponding to the amino acid residues 106 to 124 of the SEMA domain amino acid sequence (SEQ ID NO: 79) of c-Met protein, is a loop region between the second and the third propellers within the epitopes of the SEMA domain. The region acts as an epitope for the specific anti-c-Met antibody of the present disclosure.

The term “epitope” as used herein, refers to an antigenic determinant, a part of an antigen recognized by an antibody. In one embodiment, the epitope may be a region including 5 or more contiguous (consecutive or non-consecutive) amino acid residues within the SEMA domain (SEQ ID NO: 79) of c-Met protein, for instance, 5 to 19 contiguous amino acid residues within the amino acid sequence of SEQ ID NO: 71. For example, the epitope may be a polypeptide having 5 to 19 contiguous amino acids selected from among partial combinations of the amino acid sequence of SEQ ID NO: 71, wherein the polypeptide essentially includes the amino sequence of SEQ ID NO: 73 (EEPSQ) serving as an essential element for the epitope. For example, the epitope may be a polypeptide comprising, consisting essentially of, or consisting of the amino acid sequence of SEQ ID NO: 71, SEQ ID NO: 72, SEQ ID NO: 73 or a combination thereof.

The epitope having the amino acid sequence of SEQ ID NO: 72 corresponds to the outermost part of the loop between the second and third propellers within the SEMA domain of a c-Met protein. The epitope having the amino acid sequence of SEQ ID NO: 73 is a site to which the antibody or antigen-binding fragment according to one embodiment most specifically binds.

Thus, the anti-c-Met antibody may specifically bind to an epitope which has 5 to 19 contiguous amino acids selected from among partial combinations of the amino acid sequence of SEQ ID NO: 71, including SEQ ID NO: 73 as an essential element. For example, the anti-c-Met antibody may specifically bind to an epitope including the amino acid sequence of SEQ ID NO: 71, SEQ ID NO: 72, or SEQ ID NO: 73.

In a particular embodiment, the anti-c-Met antibody may be an antibody or an antigen-binding fragment thereof, which includes:

a heavy chain variable region including at least one heavy chain complementarity determining region (CDR) selected from the group consisting of (a) a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 4; (b) a CDR-H2 comprising the amino acid sequence of SEQ ID NO: 5, SEQ ID NO: 2, or an amino acid sequence comprising 8-19 consecutive amino acids of SEQ ID NO: 2 including amino acid residues from the 3^(rd) to 10^(th) positions of SEQ ID NO: 2; and (c) a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 6, SEQ ID NO: 85, or an amino acid sequence comprising 6-13 consecutive amino acids of SEQ ID NO: 85 including amino acid residues from the 1^(st) to 6^(th) positions of SEQ ID NO: 85; and

a light chain variable region including at least one light chain complementarity determining region (CDR) selected from the group consisting of (a) a CDR-L1 comprising the amino acid sequence of SEQ ID NO: 7, (b) a CDR-L2 comprising the amino acid sequence of SEQ ID NO: 8, and (c) a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 9, SEQ ID NO: 86, or an amino acid sequence comprising 9-17 consecutive amino acids of SEQ ID NO: 89 including amino acid residues from the 1^(st) to 9^(th) positions of SEQ ID NO: 89.

Herein, the amino acid sequences of SEQ ID NOS: 4 to 9 are respectively represented by following Formulas I to VI, below:

Formula I (SEQ ID NO: 4) Xaa₁-Xaa₂-Tyr-Tyr-Met-Ser,

wherein Xaa₁ is absent or Pro or Ser, and Xaa₂ is Glu or Asp,

Formula II (SEQ ID NO: 5) Arg-Asn-Xaa₃-Xaa₄-Asn-Gly-Xaa₅-Thr, 

wherein Xaa₃ is Asn or Lys, Xaa₄ is Ala or Val, and Xaa₅ is Asn or Thr,

Formula III (SEQ ID NO: 6) Asp-Asn-Trp-Leu-Xaa₆-Tyr,

wherein Xaa₆ is Ser or Thr,

Formula IV (SEQ ID NO: 7) Lys-Ser-Ser-Xaa₇-Ser-Leu-Leu-Ala- Xaa₈-Gly-Asn-Xaa₉-Xaa₁₀-Asn-Tyr-Leu-Ala

wherein Xaa₇ is His, Arg, Gln, or Lys, Xaa₈ is Ser or Trp, Xaa₉ is His or Gln, and Xaa₁₀ is Lys or Asn,

Formula V (SEQ ID NO: 8) Trp-Xaa₁₁-Ser-Xaa₁₂-Arg-Val-Xaa₁₃ 

wherein Xaa₁₁ is Ala or Gly, Xaa₁₂ is Thr or Lys, and Xaa₁₃ is Ser or Pro, and

Formula VI (SEQ ID NO: 9) Xaa₁₄-Gln-Ser-Tyr-Ser-Xaa₁₅-Pro-Xaa₁₆-Thr

wherein Xaa₁₄ is Gly, Ala, or Gln, Xaa₁₅ is Arg, His, Ser, Ala, Gly, or Lys, and Xaa₁₆ is Leu, Tyr, Phe, or Met.

In a particular embodiment, the CDR-H1 may have an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 22, 23, and 24. The CDR-H2 may have an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 25, and 26. The CDR-H3 may have an amino acid sequence selected from the group consisting of SEQ ID NOS: 3, 27, 28, and 85.

The CDR-L1 may have an amino acid sequence selected from the group consisting of SEQ ID NOS: 10, 29, 30, 31, 32, 33, and 106. The CDR-L2 may have an amino acid sequence selected from the group consisting of SEQ ID NOS: 11, 34, 35, and 36. The CDR-L3 may have an amino acid sequence selected from the group consisting of SEQ ID NOS: 12, 13, 14, 15, 16, 37, 86, and 89.

In another embodiment, the antibody or the antigen-binding fragment may include a heavy variable region including a polypeptide (CDR-H1) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 22, 23, and 24, a polypeptide (CDR-H2) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 25, and 26, and a polypeptide (CDR-H3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 3, 27, 28, and 85; and a light variable region including a polypeptide (CDR-L1) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 10, 29, 30, 31, 32, 33 and 106, a polypeptide (CDR-L2) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 11, 34, 35, and 36, and a polypeptide (CDR-L3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS 12, 13, 14, 15, 16, 37, 86, and 89.

Animal-derived antibodies produced by immunizing non-immune animals with a desired antigen generally invoke immunogenicity when injected to humans for the purpose of medical treatment, and thus chimeric antibodies have been developed to inhibit such immunogenicity. Chimeric antibodies are prepared by replacing constant regions of animal-derived antibodies that cause an anti-isotype response with constant regions of human antibodies by genetic engineering. Chimeric antibodies are considerably improved in an anti-isotype response compared to animal-derived antibodies, but animal-derived antibodies still have variable regions, so that chimeric antibodies have side effects with respect to a potential anti-idiotype response. Humanized antibodies have been developed to reduce such side effects. Humanized antibodies are produced by grafting complementarity determining regions (CDR) which serve an important role in antigen binding in variable regions of chimeric antibodies into a human antibody framework.

In using CDR grafting to produce humanized antibodies, it is important to correctly choose optimized human antibodies for accepting CDRs of animal-derived antibodies. Antibody databases, analysis of a crystal structure, and technology for molecule modeling are used. However, even when the CDRs of animal-derived antibodies are grafted to the most optimized human antibody framework, amino acids positioned in a framework of the animal-derived CDRs affecting antigen binding are present. Therefore, in many cases, antigen binding affinity is not maintained, and thus application of additional antibody engineering technology for recovering the antigen binding affinity is necessary.

The anti c-Met antibodies may be, but are not limited to, mouse-derived antibodies, mouse-human chimeric antibodies, humanized antibodies, or human antibodies. The antibodies or antigen-binding fragments thereof may be isolated from (that is, not originally present in) a living body or non-naturally occurring. The antibodies or antigen-binding fragments may be monoclonal or synthetic.

An intact antibody includes two full-length light chains and two full-length heavy chains, in which each light chain is linked to a heavy chain by disulfide bonds. The antibody has a heavy chain constant region and a light chain constant region. The heavy chain constant region is of a gamma (γ), mu (μ), alpha (α), delta (δ), or epsilon (ε) type, which may be further categorized as gamma 1 (γ1), gamma 2(γ2), gamma 3(γ3), gamma 4(γ4), alpha 1(α1), or alpha 2(α2). The light chain constant region is of either a kappa (κ) or lambda (λ) type.

As used herein, the term “heavy chain” refers to full-length heavy chain, and fragments thereof, including a variable region V_(H) that includes amino acid sequences sufficient to provide specificity to antigens, and three constant regions, C_(H1), C_(H2), and C_(H3), and a hinge. The term “light chain” refers to a full-length light chain and fragments thereof, including a variable region V_(L) that includes amino acid sequences sufficient to provide specificity to antigens, and a constant region C_(L).

The term “complementarity determining region (CDR)” refers to an amino acid sequence found in a hyper variable region of a heavy chain or a light chain of immunoglobulin. The heavy and light chains may respectively include three CDRs (CDRH1, CDRH2, and CDRH3; and CDRL1, CDRL2, and CDRL3). The CDR may provide contact residues that play an important role in the binding of antibodies to antigens or epitopes. The terms “specifically binding” and “specifically recognized” are well known to one of ordinary skill in the art, and indicate that an antibody and an antigen specifically interact with each other to lead to an immunological activity.

The “antigen binding fragment” refers to a fragment of a full immunoglobulin structure including parts of the polypeptide including antigen-binding regions capable of binding to an antigen. For example, the antigen binding fragment may be scFv, (scFv)₂, Fab, Fab′, or F(ab′)₂, but not limited thereto.

Of the antigen binding fragments, Fab is a structure having variable regions of a light chain and a heavy chain, a constant region of the light chain, and the first constant region (C_(H1)) of the heavy chain, and it has one antigen binding site.

Fab′ is different from Fab in that it has a hinge region including one or more cysteine residues at the C-terminal of heavy chain C_(H1) domain.

F(ab′)₂ antibody is formed through disulfide bond of the cysteine residues at the hinge region of Fab′.

Fv is a minimal antibody piece having only a heavy chain variable region and light chain variable region, and a recombinant technique for producing the Fv fragment is well known in the pertinent art.

Two-chain Fv may have a structure in which the heavy chain variable region is linked to the light chain variable region by a non-covalent bond, and single-chain Fv (scFv) may generally have a dimer structure as in the two-chain Fv in which the variable region of a heavy chain and the variable region of a light chain are covalently linked via a peptide linker or they are directly linked to each other at the C-terminal thereof. The peptide linker may be the same as described above, for example, those having an amino acid length of 1 to 100, 2 to 50, particularly 5 to 25, and any amino acid residues may be included therein without any restriction.

The antigen binding fragments may be obtained using proteases (e.g., a whole antibody is digested with papain to obtain Fab fragments, and is digested with pepsin to obtain F(ab′)₂ fragments), and may be prepared by a genetic recombinant technique.

The term “hinge region,” as used herein, refers to a region between CH1 and CH2 domains within the heavy chain of an antibody which functions to provide flexibility for the antigen-binding site.

When an animal antibody undergoes a chimerization process, the IgG1 hinge of animal origin may be replaced with a human IgG1 hinge or IgG2 hinge while the disulfide bridges between two heavy chains are reduced from three to two in number. In addition, an animal-derived IgG1 hinge is shorter than a human IgG1 hinge. Accordingly, the rigidity of the hinge is changed. Thus, a modification of the hinge region may bring about an improvement in the antigen binding efficiency of the humanized antibody. The modification of the hinge region through amino acid deletion, addition, or substitution is well-known to those skilled in the art.

In one embodiment, the anti-c-Met antibody or an antigen-binding fragment thereof may be modified by the deletion, insertion, addition, or substitution of at least one amino acid residue on the amino acid sequence of the hinge region, so that it exhibits enhanced antigen-binding efficiency. For example, the antibody may include a hinge region having the amino acid sequence of SEQ ID NO: 100(U7-HC6), 101(U6-HC7), 102(U3-HC9), 103(U6-HC8), or 104(U8-HC5), or a hinge region having the amino acid sequence of SEQ ID NO: 105 (non-modified human hinge). Preferably, the hinge region has the amino acid sequence of SEQ ID NO: 100 or 101.

In one embodiment of the anti-c-Met antibody or antigen-binding fragment, the variable domain of the heavy chain has the amino acid sequence of SEQ ID NO: 17, 74, 87, 90, 91, 92, 93, or 94 and the variable domain of the light chain has the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 75, 88, 95, 96, 97, 98, 99, or 107.

In one embodiment, the anti-c-Met antibody may be a monoclonal antibody. The monoclonal antibody may be produced by the hybridoma cell line deposited under Accession No. KCLRF-BP-00220, which binds specifically to the extracellular region of c-Met protein (refer to Korean Patent Publication No. 2011-0047698, the entire disclosures of which are incorporated herein by reference). The anti-c-Met antibody may include all the antibodies defined in Korean Patent Publication No. 2011-0047698.

In the anti-c-Met antibody, the remaining portion of the light chain and the heavy chain portion excluding the CDRs, the light chain variable region, and the heavy chain variable region as defined above, that is the light chain constant region and the heavy chain constant region, may be those from any subtype of immunoglobulin (e.g., IgA, IgD, IgE, IgG (IgG1, IgG2, IgG3, IgG4), IgM).

By way of further example, the anti-c-Met antibody or the antibody fragment may include:

a heavy chain having the amino acid sequence selected from the group consisting of the amino acid sequence of SEQ ID NO: 62 (wherein the amino acid residues from the 1^(st) to 17^(th) positions constitute a signal peptide), or the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62, the amino acid sequence of SEQ ID NO: 64 (wherein the amino acid residues from the 1^(st) to 17^(th) positions constitute a signal peptide), the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64, the amino acid sequence of SEQ ID NO: 66 (wherein the amino acid residues from the 1^(st) to 17^(th) positions constitute a signal peptide), and the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66; and

a light chain having the amino acid sequence selected from the group consisting of the amino acid sequence of SEQ ID NO: 68 (wherein the amino acid residues from the 1^(st) to 20^(th) positions constitute a signal peptide), the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68, the amino acid sequence of SEQ ID NO: 70 (wherein the amino acid residues from the 1^(st) to 20^(th) positions constitute a signal peptide), the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70, and the amino acid sequence of SEQ ID NO: 108.

For example, the anti-c-Met antibody may be selected from the group consisting of:

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 62 or the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62 and a light chain comprising the amino acid sequence of SEQ ID NO: 68 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68;

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 64 or the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64 and a light chain comprising the amino acid sequence of SEQ ID NO: 68 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68;

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 66 or the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66 and a light chain comprising the amino acid sequence of SEQ ID NO: 68 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68;

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 62 or the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62 and a light chain comprising the amino acid sequence of SEQ ID NO: 70 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70;

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 64 or the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64 and a light chain comprising the amino acid sequence of SEQ ID NO: 70 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70;

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 66 or the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66 and a light chain comprising the amino acid sequence of SEQ ID NO: 70 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70;

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 62 or the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62 and a light chain comprising the amino acid sequence of SEQ ID NO: 108;

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 64 or the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64 and a light chain comprising the amino acid sequence of SEQ ID NO: 108; and

an antibody including a heavy chain comprising the amino acid sequence of SEQ ID NO: 66 or the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66 and a light chain comprising the amino acid sequence of SEQ ID NO: 108.

The polypeptide of SEQ ID NO: 70 is a light chain including the human kappa (κ) constant region, and the polypeptide with the amino acid sequence of SEQ ID NO: 68 is a polypeptide obtained by replacing histidine at position 62 (corresponding to position 36 of SEQ ID NO: 68 according to kabat numbering) of the polypeptide with the amino acid sequence of SEQ ID NO: 70 with tyrosine. The production yield of the antibodies may be increased by the replacement. The polypeptide with the amino acid sequence of SEQ ID NO: 108 is a polypeptide obtained by replacing serine with tryptophan at position 32 (position 27e according to kabat numbering) in the amino acid sequence from amino acid residues 21 to 240 of SEQ ID NO: 68; positioned within CDR-L1. By such replacement, antibodies and antibody fragments including such sequences exhibits increased activities, such as c-Met biding affinity, c-Met degradation activity, Akt phosphorylation inhibition, and the like.

In another embodiment, the anti c-Met antibody may include a light chain complementarity determining region having the amino acid sequence of SEQ ID NO: 106, a light chain variable region comprising the amino acid sequence of SEQ ID NO: 107, or a light chain comprising the amino acid sequence of SEQ ID NO: 108.

The present disclosure pertains to a composition for stabilizing physical, chemical and/or biological properties of a protein drug, for example, an antibody, particularly an anti-c-Met antibody for a long period of time, and a liquid formulation in which the antibody can be stored for a long period of time without deteriorating in terms of physical, chemical and/or biological properties. The following effects are expected:

1) Suppression of antibody particle formation, aggregation and/or fragmentation, which might occur during the storage thereof, can be suppressed, thereby maintaining the pharmaceutical efficacy of the antibody for a long period of time.

2) The long-term maintenance of pharmaceutical efficacy brings about a reduction in the number of antibodies produced and the cost of antibody production, resulting in an economical benefit.

3) The composition of the liquid formulation may be provided as a base on which various formulations with high stability can be developed.

EXAMPLES

It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.

Reference Example 1 Construction of Anti-c-Met Antibody

1.1. Production of “AbF46”, a Mouse Antibody to c-Met

1.1.1. Immunization of Mouse

To obtain immunized mice necessary for the development of a hybridoma cell line, each of five BALB/c mice (Japan SLC, Inc.), 4 to 6 weeks old, was intraperitoneally injected with a mixture of 100 μg of human c-Met/Fc fusion protein (R&D Systems) and one volume of complete Freund's adjuvant. Two weeks after the injection, a second intraperitoneal injection was conducted on the same mice with a mixture of 50 μg of human c-Met/Fc protein and one volume of incomplete Freund's adjuvant. One week after the second immunization, the immune response was finally boosted. Three days later, blood was taken from the tails of the mice and the sera were 1/1000 diluted in PBS and used to examine a titer of antibody to c-Met by ELISA. Mice found to have a sufficient antibody titer were selected for use in the cell fusion process.

1.1.2. Cell Fusion and Production of Hybridoma

Three days before cell fusion, BALB/c mice (Japan SLC, Inc.) were immunized with an intraperitoneal injection of a mixture of 50 μg of human c-Met/Fc fusion protein and one volume of PBS. The immunized mice were anesthetized before excising the spleen from the left half of the body. The spleen was meshed to separate splenocytes which were then suspended in a culture medium (DMEM, GIBCO, Invitrogen). The cell suspension was centrifuged to recover the cell layer. The splenocytes thus obtained (1×10⁸ cells) were mixed with myeloma cells (Sp2/0) (1×10⁸ cells), followed by spinning to give a cell pellet. The cell pellet was slowly suspended, treated with 45% polyethylene glycol (PEG) (1 mL) in DMEM for 1 min at 37° C., and supplemented with 1 mL of DMEM. To the cells was added 10 mL of DMEM over 10 min, after which incubation was conducted in a water bath at 37° C. for 5 min. Then the cell volume was adjusted to 50 mL before centrifugation. The cell pellet thus formed was resuspended at a density of 1-2×10⁵ cells/mL in a selection medium (HAT medium) and 0.1 mL of the cell suspension was allocated to each well of 96-well plates which were then incubated at 37° C. in a CO₂ incubator to establish a hybridoma cell population.

1.1.3. Selection of Hybridoma Cells Producing Monoclonal Antibodies to c-Met Protein

From the hybridoma cell population established in Reference Example 1.1.2, hybridoma cells which showed a specific response to c-Met protein were screened by ELISA using human c-Met/Fc fusion protein and human Fc protein as antigens.

Human c-Met/Fc fusion protein was seeded in an amount of 50 μL (2 μg/mL)/well to microtiter plates and allowed to adhere to the surface of each well. The antibody that remained unbound was removed by washing. For use in selecting the antibodies that do not bind c-Met but recognize Fc, human Fc protein was attached to the plate surface in the same manner.

The hybridoma cell culture obtained in Reference Example 1.1.2 was added in an amount of 50 μL to each well of the plates and incubated for 1 hour. The cells remaining unreacted were washed out with a sufficient amount of Tris-buffered saline and Tween 20 (TBST). Goat anti-mouse IgG-horseradish peroxidase (HRP) was added to the plates and incubated for 1 hour at room temperature. The plates were washed with a sufficient amount of TBST, followed by reacting the peroxidase with a substrate (OPD). Absorbance at 450 nm was measured on an ELISA reader.

Hybridoma cell lines which secrete antibodies that specifically and strongly bind to human c-Met but not human Fc were selected repeatedly. From the hybridoma cell lines obtained by repeated selection, a single clone producing a monoclonal antibody was finally separated by limiting dilution. The single clone of the hybridoma cell line producing the monoclonal antibody was deposited with the Korean Cell Line Research Foundation, an international depository authority located at Yungun-Dong, Jongno-Gu, Seoul, Korea, on Oct. 9, 2009, with Accession No. KCLRF-BP-00220 according to the Budapest Treaty (refer to Korean Patent Laid-Open Publication No. 2011-0047698).

1.1.4. Production and Purification of Monoclonal Antibody

The hybridoma cell line obtained in Reference Example 1.1.3 was cultured in a serum-free medium, and the monoclonal antibody (AbF46) was produced and purified from the cell culture.

First, the hybridoma cells cultured in 50 mL of a medium (DMEM) supplemented with 10% (v/v) FBS were centrifuged and the cell pellet was washed twice or more with 20 mL of PBS to remove the FBS therefrom. Then, the cells were resuspended in 50 mL of DMEM and incubated for 3 days at 37° C. in a CO₂ incubator.

After the cells were removed by centrifugation, the supernatant was stored at 4° C. before use or immediately used for the separation and purification of the antibody. An AKTA system (GE Healthcare) equipped with an affinity column (Protein G agarose column; Pharmacia, USA) was used to purify the antibody from 50 to 300 mL of the supernatant, followed by concentration with a filter (Amicon). The antibody in PBS was stored before use in the following examples.

1.2. Construction of chAbF46, a Chimeric Antibody to c-Met

A mouse antibody is apt to elicit immunogenicity in humans. To solve this problem, chAbF46, a chimeric antibody, was constructed from the mouse antibody AbF46 produced in Experimental Example 1.1.4 by replacing the constant region, but not the variable region responsible for antibody specificity, with an amino sequence of the human IgG1 antibody.

For this purpose, a gene was designed to include the nucleotide sequence of “EcoRI-signal sequence-VH-Nhel-CH-TGA-Xhol” (SEQ ID NO: 38), coding for a heavy chain and the nucleotide sequence of “EcoRI-signal sequence-VL-BsiWI-CL-TGA-Xhol” (SEQ ID NO: 39), coding for a light chain and was synthesized. Then, a DNA fragment having the heavy chain nucleotide sequence (SEQ ID NO: 38) and a DNA fragment having the light chain nucleotide sequence (SEQ ID NO: 39) were digested with EcoRI (NEB, R0101S) and Xhol (NEB, R0146S) before cloning into a pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen), and a pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01), respectively.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using Freestyle™ MAX 293 Expression System (invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. One day prior to transient expression, the cells were suspended at a concentration of 5×10⁵ cells/ml, and after 24 hours, when the cell number reached 1×10⁶ cells/ml, transient expression was initiated. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (invitrogen), wherein the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) in a 15 ml tube and mixed with 2 ml of OptiPro™ SFM (invitrogen) (A), and in another 15 ml tube, 100 ul (microliter) of Freestyle™ MAX reagent and 2 ml of OptiPro™ SFM were mixed (B), followed by mixing (A) and (B) together and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day prior to transient expression initiation. After completing the transfection, the cells were incubated in a 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

Afterwards, the cells were incubated in DMEM supplemented with 10% (v/v) FBS for 5 hours at 37° C. under a 5% CO₂ condition and then in FBS-free DMEM for 48 hours at 37° C. under a 5% CO₂ condition.

After centrifugation, the supernatant was applied to AKTA prime (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime equipped with a Protein A column (GE healthcare, 17-0405-03), followed by elution with an IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to purify a chimeric antibody AbF46 (hereinafter referred to as “chAbF46”).

1.3. Construction of Humanized Antibody huAbF46 from Chimeric Antibody chAbF46

1.3.1. Heavy Chain Humanization

To design two domains, H1-heavy and H3-heavy, human germline genes which share the highest identity/homology with the VH gene of the mouse antibody AbF46 purified in Reference Example 1.2 were analyzed. An Ig BLAST (www.ncbi.nlm.nih.gov/igblast/) result revealed that VH3-71 has an identity/identity/homology of 83% at the amino acid level. CDR-H1, CDR-H2, and CDR-H3 of the mouse antibody AbF46 were defined according to Kabat numbering. A design was made to introduce the CDR of the mouse antibody AbF46 into the framework of VH3-71. Hereupon, back mutations to the amino acid sequence of the mouse AbF46 were conducted at positions 30 (S→T), 48 (V→L), 73 (D→N), and 78 (T→L). Then, H1 was further mutated at positions 83 (R→K) and 84 (A→T) to finally establish H1-heavy (SEQ ID NO: 40) and H3-heavy (SEQ ID NO: 41).

For use in designing H4-heavy, human antibody frameworks were analyzed by a BLAST search. The result revealed that the VH3 subtype, known to be most stable, is very similar in framework and sequence to the mouse antibody AbF46. CDR-H1, CDR-H2, and CDR-H3 of the mouse antibody AbF46 were defined according to Kabat numbering and introduced into the VH3 subtype to construct H4-heavy (SEQ ID NO: 42).

1.3.2. Light Chain Humanization

To design two domains, H1-light (SEQ ID NO: 43) and H2-light (SEQ ID NO: 44), human germline genes which share the highest identity/homology with the VH gene of the mouse antibody AbF46 were analyzed. An Ig BLAST search result revealed that VK4-1 has an identity/homology of 75% at the amino acid level. CDR-L1, CDR-L2, and CDR-L3 of the mouse antibody AbF46 were defined according to Kabat numbering. A design was made to introduce the CDR of the mouse antibody AbF46 into the framework of VK4-1. Hereupon, back mutations to the amino acid sequence of the mouse AbF46 were conducted at positions 36 (Y→H), 46 (L→M), and 49 (Y→I). Only one back mutation was conducted at position 49 (Y→I) on H2-light.

To design H3-light (SEQ ID NO: 45), human germline genes which share the highest identity/homology with the VL gene of the mouse antibody AbF46 were analyzed by a search for BLAST. As a result, VK2-40 was selected. VL and VK2-40 of the mouse antibody AbF46 were found to have a identity/homology of 61% at an amino acid level. CDR-L1, CDR-L2, and CDR-L3 of the mouse antibody were defined according to Kabat numbering and introduced into the framework of VK4-1. Back mutations were conducted at positions 36 (Y→H), 46 (L→M), and 49 (Y→I) on H3-light.

For use in designing H4-light (SEQ ID NO: 46), human antibody frameworks were analyzed. A Blast search revealed that the Vk1 subtype, known to be the most stable, is very similar in framework and sequence to the mouse antibody AbF46. CDR-L1, CDR-L2, and CDR-L3 of the mouse antibody AbF46 were defined according to Kabat numbering and introduced into the Vk1 subtype. Hereupon, back mutations were conducted at positions 36 (Y→H), 46 (L→M), and 49 (Y→I) on H4-light.

Thereafter, DNA fragments comprising the heavy chain nucleotide sequences (H1-heavy: SEQ ID NO: 47, H3-heavy: SEQ ID NO: 48, H4-heavy: SEQ ID NO: 49) and DNA fragments comprising the light chain nucleotide sequences (H1-light: SEQ ID NO: 50, H2-light: SEQ ID NO: 51, H3-light: SEQ ID NO: 52, H4-light: SEQ ID NO: 53) were digested with EcoRI (NEB, R0101S) and Xhol (NEB, R0146S) before cloning into a pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen) and a pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01), respectively, so as to construct recombinant vectors for expressing a humanized antibody.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using Freestyle™ MAX 293 Expression System (invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. One day prior to the transient expression, the cells were suspended at a concentration of 5×10⁵ cells/ml, and after 24 hours, when the cell number reached to 1×10⁶ cells/ml, the transient expression was initiated. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (invitrogen), wherein the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) in a 15 ml tube and mixed with 2 ml of OptiPro™ SFM (invitrogen) (A), and in another 15 ml tube, 100 ul (microliter) of Freestyle™ MAX reagent and 2 ml of OptiPro™ SFM were mixed (B), followed by mixing (A) and (B) together and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day prior to transient expression initiation. After completing the transfection, the cells were incubated in a 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

After centrifugation, the supernatant was applied to AKTA prime (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime equipped with a Protein A column (GE healthcare, 17-0405-03), followed by elution with an IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to purify a humanized antibody AbF46 (hereinafter referred to as “huAbF46”). The humanized antibody huAbF46 used in the following examples included a combination of H4-heavy (SEQ ID NO: 42) and H4-light (SEQ ID NO: 46).

1.4. Construction of scFV Library of huAbF46 Antibody

For use in constructing an scFv of the huAbF46 antibody from the heavy and light chain variable regions of the huAbF46 antibody, a gene was designed to have the structure of “VH-linker-VL” for both the heavy and the light chain variable regions, with the linker having the amino acid sequence “GLGGLGGGGSGGGGSGGSSGVGS” (SEQ ID NO: 54). A polynucleotide sequence (SEQ ID NO: 55) encoding the designed scFv of huAbF46 was synthesized in Bioneer and an expression vector for the synthesized polynucleotide comprised the nucleotide sequence of SEQ ID NO: 56.

After expression, the product was found to exhibit specificity to c-Met.

1.5. Construction of Library Genes for Affinity Maturation

1.5.1. Selection of Target CDRs and Synthesis of Primers

The affinity maturation of huAbF46 was achieved. First, six complementary determining regions (CDRs) were defined according to Kabat numbering. The CDRs are given in Table 1, below.

TABLE 1 CDR Amino Acid Sequence CDR-H1 DYYMS (SEQ ID NO: 1) CDR-H2 FIRNKANGYTTEYSASVKG (SEQ ID NO: 2) CDR-H3 DNWFAY (SEQ ID NO: 3) CDR-L1 KSSQSLLASGNQNNYLA (SEQ ID NO: 10) CDR-L2 WASTRVS (SEQ ID NO: 11) CDR-L3 QQSYSAPLT (SEQ ID NO: 12)

For the purpose of introducing random sequences into the CDRs of the antibody, primers were designed as follows. Conventionally, N codons were utilized to introduce bases at the same ratio (25% A, 25% G, 25% C, 25% T) into desired sites of mutation. In this experiment, the introduction of random bases into the CDRs of huAbF46 was conducted in such a manner that, of the three nucleotides per wild-type codon encoding each amino acid of CDR, 85% of the first nucleotide was conserved while the other three nucleotides were introduced at the same percentage (each 5%); 85% of the second nucleotide was conserved while the other three nucleotides were introduced into the rest (15%) of the second nucleotide at the same percentage (each 5%); and G, C and T were introduced into the third nucleotide at the same percentage (33% G, 33% C, 33% T).

1.5.2. Construction of a Library of huAbF46 Antibodies and Affinity for c-Met

The construction of antibody gene libraries through the introduction of random sequences was carried out using the primers synthesized in the same manner as in Reference Example 1.5.1. Two PCR products were obtained using a polynucleotide covering the scFV of huAbF46 as a template, and were subjected to overlap extension PCR to give scFv library genes for huAbF46 antibodies in which only desired CDRs were mutated. Libraries targeting each of the six CDRs prepared from the scFV library genes were constructed.

The affinity for c-Met of each library was compared to that of the wildtype. Most libraries were lower in affinity for c-Met, compared to the wild-type. The affinity for c-Met was retained in some mutants.

1.6. Selection of Antibody with Improved Affinity from Libraries

After maturation of the affinity of the constructed libraries for c-Met, the nucleotide sequence of scFv from each clone was analyzed. The nucleotide sequences thus obtained are summarized in Table 2 and were converted into IgG forms. Four antibodies which were respectively produced from clones L3-1, L3-2, L3-3, and L3-5 were used in the subsequent experiments.

TABLE 2 Library con- Clone structed CDR Sequence H11-4 CDR-H1 PEYYMS (SEQ ID NO: 22) YC151 CDR-H1 PDYYMS (SEQ ID NO: 23) YC193 CDR-H1 SDYYMS (SEQ ID NO: 24) YC244 CDR-H2 RNNANGNT (SEQ ID NO: 25) YC321 CDR-H2 RNKVNGYT (SEQ ID NO: 26) YC354 CDR-H3 DNWLSY (SEQ ID NO: 27) YC374 CDR-H3 DNWLTY (SEQ ID NO: 28) L1-1 CDR-L1 KSSHSLLASGNQNNYLA (SEQ ID NO: 29) L1-3 CDR-L1 KSSRSLLSSGNHKNYLA (SEQ ID NO: 30) L1-4 CDR-L1 KSSKSLLASGNQNNYLA (SEQ ID NO: 31) L1-12 CDR-L1 KSSRSLLASGNQNNYLA (SEQ ID NO: 32) L1-22 CDR-L1 KSSHSLLASGNQNNYLA (SEQ ID NO: 33) L2-9 CDR-L2 WASKRVS (SEQ ID NO: 34) L2-12 CDR-L2 WGSTRVS (SEQ ID NO: 35) L2-16 CDR-L2 WGSTRVP (SEQ ID NO: 36) L3-1 CDR-L3 QQSYSRPYT (SEQ ID NO: 13) L3-2 CDR-L3 GQSYSRPLT (SEQ ID NO: 14) L3-3 CDR-L3 AQSYSHPFS (SEQ ID NO: 15) L3-5 CDR-L3 QQSYSRPFT (SEQ ID NO: 16) L3-32 CDR-L3 QQSYSKPFT (SEQ ID NO: 37)

1.7. Conversion of Selected Antibodies into IgG

Respective polynucleotides encoding heavy chains of the four selected antibodies were designed to have the structure of “EcoRI-signal sequence-VH-Nhel-CH-Xhol” (SEQ ID NO: 38). The heavy chains of huAbF46 antibodies were used as they were because their amino acids were not changed during affinity maturation. In the case of the hinge region, however, the U6-HC7 hinge (SEQ ID NO: 57) was employed instead of the hinge of human IgG1. Genes were also designed to have the structure of “EcoRI-signal sequence-VL-BsiWI-CL-Xhol” for the light chain. Polypeptides encoding light chain variable regions of the four antibodies which were selected after the affinity maturation were synthesized in Bioneer. Then, a DNA fragment having the heavy chain nucleotide sequence (SEQ ID NO: 38) and DNA fragments having the light chain nucleotide sequences (DNA fragment including L3-1-derived CDR-L3: SEQ ID NO: 58, DNA fragment including L3-2-derived CDR-L3: SEQ ID NO: 59, DNA fragment including L3-3-derived CDR-L3: SEQ ID NO: 60, and DNA fragment including L3-5-derived CDR-L3: SEQ ID NO: 61) were digested with EcoRI (NEB, R0101S) and Xhol (NEB, R0146S) before cloning into a pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen) and a pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01), respectively, so as to construct recombinant vectors for expressing affinity-matured antibodies.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using the Freestyle™ MAX 293 Expression System (invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. One day prior to transient expression initiation, the cells were suspended at a concentration of 5×10⁵ cells/ml, and after 24 hours, when the cell number reached to 1×10⁶ cells/ml, the transient expression was initiated. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (invitrogen), wherein the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) in a 15 ml tube and mixed with 2 ml of OptiPro™ SFM (invitrogen) (A), and in another 15 ml tube, 100 ul (microliter) of Freestyle™ MAX reagent and 2 ml of OptiPro™ SFM were mixed (B), followed by mixing (A) and (B) together and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day before the transient expression. After completing the transfection, the cells were incubated in a 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

After centrifugation, the supernatant was applied to AKTA prime (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime equipped with a Protein A column (GE healthcare, 17-0405-03), followed by elution with an IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to purify four affinity-matured antibodies (hereinafter referred to as “huAbF46-H4-A1 (L3-1 origin), huAbF46-H4-A2 (L3-2 origin), huAbF46-H4-A3 (L3-3 origin), and huAbF46-H4-A5 (L3-5 origin),” respectively).

1.8. Construction of Constant Region- and/or Hinge Region-Substituted huAbF46-H4-A1

Among the four antibodies selected in Reference Example 1.7, huAbF46-H4-A1 was found to be the highest in affinity for c-Met and the lowest in Akt phosphorylation and c-Met degradation degree. In the antibody, the hinge region, or the constant region and the hinge region, were substituted.

The antibody huAbF46-H4-A1 (U6-HC7) was composed of a heavy chain including the heavy chain variable region of huAbF46-H4-A1, U6-HC7 hinge, and the constant region of human IgG1 constant region, and a light chain including the light chain variable region of huAbF46-H4-A1 and human kappa constant region. The antibody huAbF46-H4-A1 (IgG2 hinge) was composed of a heavy chain including a heavy chain variable region, a human IgG2 hinge region, and a human IgG1 constant region, and a light chain including the light chain variable region of huAbF46-H4-A1 and a human kappa constant region. The antibody huAbF46-H4-A1 (IgG2 Fc) was composed of the heavy chain variable region of huAbF46-H4-A1, a human IgG2 hinge region, and a human IgG2 constant region, and a light chain including the light variable region of huAbF46-H4-A1 and a human kappa constant region. Hereupon, the histidine residue at position 36 on the human kappa constant region of the light chain was changed to tyrosine in all of the three antibodies to increase antibody production.

For use in constructing the three antibodies, a polynucleotide (SEQ ID NO: 63) encoding a polypeptide (SEQ ID NO: 62) composed of the heavy chain variable region of huAbF46-H4-A1, a U6-HC7 hinge region, and a human IgG1 constant region, a polynucleotide (SEQ ID NO: 65) encoding a polypeptide (SEQ ID NO: 64) composed of the heavy chain variable region of huAbF46-H4-A1, a human IgG2 hinge region, and a human IgG1 region, a polynucleotide (SEQ ID NO: 67) encoding a polypeptide (SEQ ID NO: 66) composed of the heavy chain variable region of huAbF46-H4-A1, a human IgG2 region, and a human IgG2 constant region, and a polynucleotide (SEQ ID NO: 69) encoding a polypeptide (SEQ ID NO: 68) composed of the light chain variable region of huAbF46-H4-A1, with a tyrosine residue instead of histidine at position 36, and a human kappa constant region were synthesized in Bioneer. Then, the DNA fragments having heavy chain nucleotide sequences were inserted into a pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen) while DNA fragments having light chain nucleotide sequences were inserted into a pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01) so as to construct vectors for expressing the antibodies.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using the Freestyle™ MAX 293 Expression System (invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. One day prior to transient expression initiation, the cells were suspended at a concentration of 5×10⁵ cells/ml, and after 24 hours, when the cell number reached to 1×10⁶ cells/ml, the transient expression was initiated. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (invitrogen), wherein the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) in a 15 ml tube and mixed with 2 ml of OptiPro™ SFM (invitrogen) (A), and in another 15 ml tube, 100 ul (microliter) of Freestyle™ MAX reagent and 2 ml of OptiPro™ SFM were mixed (B), followed by mixing (A) and (B) together and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day prior to transient expression initiation. After completing the transfection, the cells were incubated in a 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

After centrifugation, the supernatant was applied to AKTA prime (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime equipped with a Protein A column (GE healthcare, 17-0405-03), followed by elution with IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to finally purify three antibodies (huAbF46-H4-A1 (U6-HC7), huAbF46-H4-A1 (IgG2 hinge), and huAbF46-H4-A1 (IgG2 Fc)). Among the three antibodies huAbF46-H4-A1 (IgG2 Fc) was representatively selected for the following examples, and is referred to as “anti-c-Met antibody”.

For use as an analytical index in the development of a liquid formulation containing a high concentration of an anti-c-Met antibody, the degree of aggregation of antibodies was measured. Because this aggregation has a negative influence on the bioavailability of the protein drug, such as giving rise to increased immunogenicity and decreased efficacy, it can be used as an important analytical index for the development of liquid formulations.

To develop a liquid formulation of an anti-c-Met antibody, the following processes were conducted:

1) Selection of a surfactant capable of suppressing the shear stress-induced aggregation of an antibody.

2) Determination of a suitable pH condition for guaranteeing the stable maintenance of an anti-c-Met antibody in the liquid formulation through stress tests.

3) Evaluation of roles of a buffer, an osmolality-regulating agent and a surfactant in the maintenance of an anti-c-Met antibody.

Example 1 Selection of Surfactant

When a protein drug is stored in a liquid condition, the movement of the container generates a shear stress which induces the protein drug to aggregate or fragment. A surfactant is added to the liquid to suppress the shear stress-induced aggregation, thereby improving the storage stability of protein drugs and decreasing the adsorption of protein drugs onto the container.

An evaluation was made of the effect of a surfactant on the storage stability of a protein drug. In this regard, a shear stress was applied to a buffer containing a protein drug in the presence of a surfactant to induce aggregation. The degree of aggregation was measured according to the presence or absence of a surfactant, and the type of surfactants used. Polysorbate 20 and Polysorbate 80, both pharmaceutically acceptable, were employed while the degree of aggregation was measured using a Dynamic Light Scattering (DLS) apparatus.

In detail, the anti-c-Met antibody prepared in Reference Example 1.8 was added at a concentration of 25 mg/mL or greater to a buffer prepared by dissolving 150 mM NaCl (0.877% w/v) in 20 mM sodium phosphate (0.282% w/v), pH 7.4, followed by further adding a surfactant, polysorbate 20 (Merck, Cat No: 817072) or polysorbate 80 (Merck, Cat No: 817061), in an amount of 0.05% (w/v) to the buffer to afford a liquid formulation. For comparison, a control, free of a surfactant, was prepared.

A shear stress was applied at a rate of 100 RPM for 12-16 hrs at room temperature to the liquid formulations to induce aggregation. Using a particle size analyzer (Malvern), monomeric or aggregated antibodies were measured. The results are summarized in Table 3, below.

TABLE 3 Inhibition of Surfactant against Protein Aggregation under Shear Stress Avg. Diameter (nm) Intensity (%) Aggregate Aggregate Monomer (Ab aggre- Monomer (Ab aggre- (Ab intact) gated) (Ab intact) gated) Buffer (no surfactant) 10.64 689.5 42.8 57.2 Buffer + Polysorbate 20 11.36 453.6 92.4 7.6 Buffer + Polysorbate 80 11.43 240.2 97.5 2.5

As is understood from the data of Table 3, the control, free of surfactants, was greater in both the content and the size of aggregates than were the test groups containing surfactants. That is, the test groups were much less apt to allow the formation of aggregates, and thus had a lower content and a smaller size of aggregates, compared to the control. Both polysorbate 20 and polysorbate 80 were found to effectively suppress protein aggregation, with polysorbate 80 being superior. In the following Examples, thus, polysorbate 80 was employed as a surfactant.

Example 2 Determination of pH Range of Liquid Formulation

In this experiment, a pH range of a liquid formulation suitable for maintaining physical, chemical and biological stability of protein drugs was determined. Under a stressed condition (50° C.) which was set as the storage temperature, protein drugs were induced to undergo denaturation, aggregation and fragmentation within a short time. Experiments were performed in a stressed condition (50° C.) for one week before evaluation for the degree of aggregation.

In this regard, the anti-c-Met antibody prepared in Reference Example 1.8 was added at a concentration of 30 mg/mL to various buffers (20 mM sodium phosphate was mixed with 150 mM NaCl, followed by pH adjustment into 4.5, 5.5, or 6.5 with 1N HCl) to afford liquid formulations with a pH of 4.5, 5.5, or 6.5.

Using the statistical technology Response Surface Methodology, an evaluation of the extent of aggregation and fragmentation of proteins was made. In detail, the liquid formulations were incubated for one week at 50° C. in an incubator before analysis by size-exclusion high performance liquid chromatography (SE-HPLC). A mobile phase containing 50 mM sodium phosphate and 300 mM NaCl, pH 6.6, was applied at a flow rate of 0.5 mL/min to a size exclusion column (TSK G3000swxl, TOSHO) mounted to HPLC (Alliance e2695, Waters). Absorbance was measured at 280 nm. The results are given in FIG. 2. FIG. 2 is a graph of main peaks of monomers (anti-c-Met antibody) after incubation for one week in a stressed condition (50° C.). Formation of aggregates resulted in a reduction of the main peak. Of the three pH conditions, that is, pH 4.5, 5.5 and 6.5, as can be seen in FIG. 2, pH 4.5 induced the anti-c-Met antibody to rapidly aggregate while the antibody was maintained intact at pH 5.5 and 6.5. Thus, these data indicated that in order for a liquid formulation of an anti-c-Met antibody to be stable during storage, it should have a pH exceeding 4.5, for example, a pH of 5 to 8, more particularly a pH of 5 to 7.

Example 3 Effect of a Combination of Buffer, Osmolyte and Surfactant

In a liquid formulation of a protein drug, co-existence of a buffer, an osmotic pressure regulating agent (salts, saccharides, etc.), and a surfactant was found to make maximum contribution to the stability of the protein drug.

To determine a liquid formulation's pH, osmotic pressure regulating agent content, and surfactant content suitable for maintaining physical, chemical and biological stability of protein drugs therein, the statistical methodology design of experiment (DOE) was performed. Under a stressed condition (50° C.) which was set as the storage temperature, protein drugs were induced to undergo denaturation, aggregation and fragmentation within a short time. Experiments were performed in a stressed condition (50° C.) for one week before evaluation for the degree of aggregation.

The anti-c-Met antibody prepared in Reference Example 1.8 was added at a concentration of 25 mg/mL to various buffers (20 mM sodium phosphate was prepared by pH adjustment into 4.5, 5.5, or 6.5 with 1N NCI). The liquid formulations were prepared to add 0 mM, 75 mM, and 150 mM NaCl, and 0.02% (w/v), 0.06% (w/v), and 0.10% (w/v) polysorbate 80 in buffers of assorted pH.

The resulting liquid antibody formulations were subjected to a stress test for one week at 50° C., followed by evaluation for aggregation and fragmentation. Using the statistical technology Response Surface Methodology, aggregates and fragments of the antibody were quantitatively analyzed. In detail, the resulting liquid antibody formulations were incubated at 50° C. in an incubator for one week before analysis by size-exclusion high performance liquid chromatography (SE-HPLC). A mobile phase containing 50 mM sodium phosphate and 300 mM NaCl, pH 6.6, was applied at a flow rate of 0.5 mL/min to a size exclusion column (TSK G3000swxl, TOSHO) mounted to HPLC (Alliance e2695, Waters). Absorbance was measured at 280 nm. After the size-exclusion chromatography of the incubated liquid formulations, monomers (c-Met antibody) were calculated. In addition, using a nano-particle size analyzer (Malvern), the formulations were subjected to spectrophotometry to separately measure monomers and aggregates of the anti-c-Met antibody.

Results are given in FIG. 3. When the buffer had a pH of about 6.0, as can be seen in FIG. 3, the aggregation was maximally suppressed, with the content of monomers (antibody) peaking. The osmotic pressure regulating agent NaCl and the surfactant polysorbate 80 were observed to exert suppressive effects over the concentration ranges used, with no particular dose-dependency detected. Therefore, the osmotic pressure regulating agent and the surfactant may be used at the concentrations tested in this Example. However, when the liquid formulation is used as an injection, it should be almost isotonic to the blood. For this, the osmotic pressure regulating agent NaCl was used at a concentration of 150 mM in the following experiments. In addition, the concentration of polysorbate 80 was set to be 0.05% (v/w), which was found to effectively suppress the aggregation of proteins in the shear stress test of Example 1.

Example 4 Selection of Buffer

Because the pH of buffer was identified to play a crucial role in stabilizing the anti-c-Met antibody, the four buffers, citric acid, histidine, succinic acid, and sodium phosphate, were used at a concentration of 20 mM within a pH range from 5.0 to 7.0.

In buffer solutions (pH: 5.0, 5.5, 6.0, 6.5, and 7.0; each buffer 20 mM at all pH values), NaCl was dissolved at a concentration of 150 mM, followed by addition of 1 N HCl or 1 N NaOH to afford compositions with different pH values. These compositions were added to the anti-c-Met antibody prepared in Reference Example 1.8, after which buffer substitution was performed through ultrafiltration (VIVASPIN 15R, Sartorius). A surfactant (polysorbate 80; Merck, Cat No: 817061) was further added in an amount of 0.05% (w/v) to a test group of the resulting liquid antibody formulations. In all of the liquid formulations, the anti-c-Met antibody was maintained at a concentration of 25 mg/mL.

One, two and three months after storage in a stressed condition (40° C.) or at a refrigeratory temperature (2 to 8° C.), the liquid antibody formulations were analyzed for aggregation using the same method as in Example 2.

The results are given in FIGS. 4a and 4b . As can be seen in FIG. 4a , all of the 12 combinations of four buffers, citrate, histidine, succinate and sodium phosphate, with a pH range from 5 to 7 were found to be kept 95% intact without forming into aggregates and fragments. Particularly, superior stability was detected in histidine or succinate groups to the other groups. In addition, as shown in FIG. 4b , more than 98% of the antibody in all of the 12 combinations was maintained as a monomer in a refrigeratory condition (2 to 8° C.) without aggregation or fragmentation.

On the basis of the results, a selection was made of a liquid formulation of anti-c-Met antibody containing 25 mg/ml anti-c-Met antibody, 20 mM succinate, 150 mM NaCl, and 0.05% (v/w) polysorbate 80, pH 6.0.

Example 5 Assay for Efficacy of Liquid Formulation of Anti-c-Met Antibody According to Buffer

The lung cancer cell line EBC-1 (JCRB, JCRB0820) in which a c-Met receptor was overexpressed was seeded at a density of 5×10³ cells/well into 96-well plates, and incubated with 0.008, 0.04, 0.2, or 1 ug/mL of the liquid formulation prepared in Example 4 (anti-c-Met antibody 25 mg/ml, buffer (citric acid, histidine, succinic acid, or sodium phosphate) 20 mM, NaCl 150 mM and polysorbate 80 0.05% (v/w); pH: 5.0, 5.5, 6.0, 6.5, or 7.0; stored for three months in a stressed condition (40° C.)) for 72 hrs at 37° C.

Proliferation of the cells was analyzed using Cell Counting Kit-8 assay (Dojindo Molecular Technologies, Gaithersburg, Md.). In brief, after 72 hrs of incubation, the CCK8 reagent was added in an amount of 10 ul (microliter) to each well, and incubated for an additional 2.5 hrs. Inhibitory activity of the liquid formulations including the anti-c-Met antibody against cancer cell growth was determined using colorimetry.

The results are given in FIGS. 5 to 8. Relative growth rates of the lung cancer cells (EBC-1) are plotted versus concentrations of the anti-c-Met antibody using sodium phosphate in FIG. 5, succinate in FIG. 6, histidine in FIG. 7, and citric acid in FIG. 8. The primary standard curves were obtained when the anti-c-Met antibody which had been stored at −80° C. with maximum stability was used. As is understood from data of FIGS. 5 to 8, the liquid formulations of anti-c-Met antibody according to the present disclosure were found to guarantee the activity of the anti-c-Met antibody at the same level as the primary standard, even after they had been stored for three months in a stressed condition (40° C.). These date demonstrate that the anti-c-Met antibody is maintained as intact in the liquid formulation of the present disclosure as the primary standard.

Example 6 Long-Term Stability of Liquid Formulation

The long-term stability of a liquid formulation selected in Example 5 including an anti-c-Met antibody 25 mg/ml, succinate 20 mM, NaCl 150 mM, and polysorbate 80 0.05% (v/w), pH 6.0, was predicted. For this, a curve was drawn from main peaks (of anti-c-Met antibody), and extrapolated using a 1^(st) order equation to predict the stability 24 months after storage. The results are given in FIG. 9. As shown in FIG. 8, the liquid formulation was predicted to maintain the anti-c-Met antibody about 95% intact 24 months after storage.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 

What is claimed is:
 1. A method for stabilizing a protein drug, comprising admixing a protein drug with a composition for stabilization, wherein the composition for stabilization comprises a surfactant, a buffer, and a liquid medium, and has a pH from about 5 to about 8, wherein the protein drug is an anti-c-Met antibody or antigen-binding fragment thereof comprising a CDR-H1 comprising SEQ ID NO: 1, a CDR-H2 comprising SEQ ID NO: 2, a CDR-H3 comprising SEQ ID NO: 3, a CDR-L1 comprising SEQ ID NO: 10, a CDR-L2 comprising SEQ ID NO: 11, and a CDR-L3 comprising SEQ ID NO: 13; and the buffer comprises succinic acid, citric acid, or a combination thereof.
 2. The method according to claim 1, wherein the surfactant comprises one or more selected from the group consisting of polysorbate, poloxamer, polyethylene-polypropylene glycol, polyoxyethylene, and sodium dodecyl sulphate.
 3. The method according to claim 2, wherein the surfactant comprises one or more selected from the group consisting of polysorbate 20, polysorbate 40, polysorbate 60, and polysorbate
 80. 4. The method according to claim 1, wherein the amount of the surfactant in the composition for stabilization is about 0.01% to about 1% (w/v) based on the total amount of the composition for stabilization.
 5. The method according to claim 1, wherein the composition for stabilization has a pH from about 5 to about
 7. 6. The method according to claim 1, wherein the amount of the buffer in the composition for stabilization is about 0.1 to about 1% (w/v) based on the total amount of the composition for stabilization.
 7. The method according to claim 1, wherein the composition for stabilization has an osmotic pressure of about 250 to about 400 milliosmole (mOsm).
 8. The method according to claim 1, wherein the composition for stabilization further comprises an osmoregulating agent selected from the group consisting of a pharmaceutically acceptable salt, a sugar, an amino acid, and any combination thereof.
 9. The method according to claim 8, wherein the osmoregulating agent comprises one or more selected from the group consisting of sodium chloride, sodium succinate, sodium sulfate, potassium chloride, magnesium chloride, magnesium sulfate, trehalose, sucrose, mannitol, sorbitol, fructose, maltose, lactose, dextran, proline, alanine, arginine, asparagine, aspartic acid, glycine, serine, lysine, and histidine.
 10. The method according to claim 8, wherein the amount of the osmo-regulating agent in the composition for stabilization is about 0.01 to about 1% (w/v) based on the total amount of the composition for stabilization.
 11. The method according to claim 1, wherein the amount of the protein drug in the liquid formulation is about 1 mg/ml to about 200 mg/ml.
 12. The method according to claim 1, wherein about 5% or less of the initial protein drug content of the liquid formulation aggregates or degrades after the liquid formulation has been stored at about 40° C. to about 50° C. for three months.
 13. The method of claim 1, wherein the anti-c-Met antibody comprises a heavy chain comprising the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66 and a light chain comprising the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO:
 68. 